A comprehensive analysis of the ultrastructure of paramural bodies and other entities in the plasma membrane at the formation of the secondary cell walls of plants is made. The objectives of our research on the formation of paramural bodies were: to analyze the ultrastructure of the formations found between the plasma membrane and the secondary cell wall during the formation of the polysaccharide cell wall of flax phloem fibers, tension wood of poplar, seed hairs of cotton (trichome), secondary phloem fibers of hemp), to determine the origin (the cause) of these paramural bodies. The accumulated in our research material on studying the formation of the secondary cell walls of plants of different species has allowed us to contribute to the debate about some causes of plasmatubules origin in the area between the plasma membrane and cell wall, dynamics of their formation and structure. In the cases under consideration at the formation of the secondary cell wall, we deal to a greater extent with the structures arisen as a result of plasmolysis. The author concludes that the structures previously taken for plasmatubules in most cases are the Hecht's threads.